Cosmic energy overload detector

ABSTRACT

Apparatus for measuring a radiation source level by means of a detector such as a scintillator or the like, the apparatus having a signal channel for providing a source of signal pulses from the detector indicative of the radiation level to an output device, and a timer channel for preselecting a time period of signal pulse measurement. The detector output is coupled to a comparator biased for providing an output signal in response to an input indicative of an excess radiation pulse such as a cosmic energy overload, the output of the amplifier triggering a predetermined time delay for inhibiting the signal channel and timer channel for the time duration of the overload.

I United States Patent 1191 1111 3,859,532 Luitwieler Jan. 7, 1975 COSMIC ENERGY OVERLOAD DETECTOR Primar ExaminerHarold A. Dixon 11; [H.LtlLHb, Y [75] men or 21 2 we a a [a Attorney, Agent, or Firm-J0hn G. Mesaros; R. J.

Steinmeyer [73] Assignee: Beekman Instruments, Inc., Fullerton, Filedi 1973 Apparatus for measuring a radiation source level by p [21] APPL No; 344,821 means of a detector such as a scintillator or the like, the apparatus having a signal channel for providing a source of signal pulses from the detector indicative of U-S. the radiation level to an output device and a time! hannel for preseIeeting a time period of ignal pulse [58] held 9 328/116, 117, 150163, 1 measurement. The detector output is coupled to a 250/369, 336, 354 comparator biased for providing an output signal in response to an input indicative of an excess radiation References Clted pulse such as a cosmic energy overload, the output of UNITED STATES PATENTS the amplifier triggering a predetermined time delay for 2,778,949 1/1957 Borkowski et al. 250/369 inhibiting the Signal Channel and timer Channel for the 3,094,665 6/1963 Wildman 1. 328/117 time duration of the Overload- 3,246,l50 4/1966 Stoddal't et a]. 250/369 3,548,206 12/1970 Ogle et a1. 328/163 5 1 D'awmg F'gure PRESET LEVEL 16 4 1o 13 2o 22 '24 26 2a 1 f r 1 1 1 1 AMP SIGNAL 50 SIGNAL SIGNAL PRlNT PRINT E GATE SCALER ACCUM, CONTROL our 1 1a 12 46 l l l l l 422 60 one 5110 START c gig-R12- SCALER i MULTIVIBRATER SZ/ I U SWITCH 52 6 f F -V2 2. l T T T T T TIMER TIMER TIMER GATE SCALER ACCUM 36 r38 TIMER /3o BASE COSMIC ENERGY OVERLOAZDY DETECTOR" BACKGROUND OF THE INVENTION This invention relates to apparatus for measuring the cally inhibiting-the measurement during periods of cosmic energy surges. a y

In radiation source measuring apparatus, such as gamma ray measurement, a scintillator and photosensi- 11 tive element is. utilized to measure the radiation emamating fromla source in proximity thereto. The detector assembly is suitably shielded to minimize the introduction into the scintillator and photosensitive element of notwithstanding'the shielding within the detector assembly, whenextra'terrestrial disturbances occur, cosmic energy surges produce large amounts of radiation j radiation-level of a radiation source, and more particu-" larly relates to novel detecting apparatus effective to detect, count and measure the level of gamma ray radiationof a source, with provision made for automati- BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE is a partially diagrammatic partially schematic representation of a radiation source measuring apparatus including a cosmic energy overload detector in-accordance with the invention.

I DESCRIPTION OF THE PREFERRED r EMBODIMENT Referring now to the drawing, there is shown a detector assembly for mounting a sample for counting by radiation external-to the detector assembly. However,

which impinge on the scintillator, thereby creating massive crystal disturbances which overpowerthe radiation source being'measured to thereby renderthe apparatus useless for the'time duration of the cosmic energy surge. Any readings or measurement during this time period are erroneous and provide no indication of the activity level of the radiation source. I

SUMMARY'OFTHEINVENTION t Accordingly, it is an object of this invention to provide a new and improvedradiation source measuring apparatus.

It is another object of-this inventionto provide a radiation source measuringapparatushaving a cosmic energy overload detector.

It is a further object of this invention to provide a cosmic energy overload detector which -automatically inhibits the signal channel and timer ch annel of the radia tion source measuring apparatus fora time duration approximating the time of the energy surgeI I v The foregoing andother objects of the invention are accomplished by providing radiation source measuring apparatus having a detector providing pulses to a signal channel under control of a timer channel toprovide'an output indicative of the gamma ray activity "of a radia-' I bias thereof preset in a comparator'mode to generate an output in response to the outputof the detector .tion source in proximity to the detector. The detector 7 is coupled to an operational amplifier input having'the being in excess of a predetermined level, the levelbein'g indicative of, for example, a pulse output responseto a cosmic energy disturbance. The output of the operational amplifier is coupled to 'a one-shot 'multivib'rator having a predetermined time delay consistent with the anticipated time duration of the cosmic energy' dis'tur;

bance. Upon energization of the one-shot multivibrascaler- 34.

tor, signal pulses to the signal scaler of the signal chap-J nel and timing pulses to the timer scaler of the timer channel are inhibited for the time duration of thepre determined time delay to automatically eliminate useless information which would otherwise be obtained during the cosmic energy disturbance.

Other objects, features and advantages of the invention will become apparent from the following specification taken in conjunction with the accompanying drawa scintillator and photosensitive element, the detector 10 including acylindrical lead housing having viewing openings at its ends within which may be positioned a suitable photomultiplier tube 12 connected to a suitable amplifier 13 for converting light impulses received by said tube to a pulse output. The detector 10 is provided with an opening 14 extending vertically across the interior cross section of housing 16, with said opening being surrounded by a scintillator 18. This opening and signal accumulator 24. The signal accumulator 24 provides an output through a print controller 26 to a suitable print-out device 28. Thesignal scaler 22 and signal accumulator 24 are provided with a preset level input, which input may bederived on the basis of a background subtraction level or the like (such as shown in U.S.Pat. No. 3,246,l50).

A timer base generator 30 is provided for feeding a pulse time signal to timer gate 32 which opens or closes the timer channel consisting of the switchable timer scaler 34 and timer accumulator 3.6 which provides its output signal through lead 38 to the stop input of controlcircuit 40.

The control circuit40 is provided for simultaneously operating signal gate 20 and timer gate 32 either to open them when its"start, terminal 42 is operated or to close them when its stop tenninal 44 is operated by .the output signal from -timer accumulator 36 through lead 38;

. As illustrated, the switchable signal scaler 22 and timer scaler 34 are provided with a common switching 'means 46 so that they will be switched simultaneously duringselection'of a desired predetermined counting time. It is tobe understood, however, that the scaler switch 46 may be two independently operated switches, onefor the signal scaler 22 and another for the timer I The radiation source measuring apparatus thus far described, conventionally operates by insertion of a preset level input into the signal scaler 22 and signal accumulator 24, appropriate setting of the scaler switch 46 to the desired predetermined counting time, with the signals indicative of the activity level of the radiation source being transmitted along the signal channel under control of the timer channel. The signal pulses emanating from photomultiplier tube 12 are generally,

' 'fycosinic energy pulses affecting the scintillator 18 and photornultiplier tube [12 will generate pulses in the "order of magnitude 'of m 20 volts, and oftentimes cos- Provision is also made for compensation for counting errors at high sample count rates during the length of time the scaler is inhibited by inhibiting the timing pulsestothe timer gate 32 for the length of time the sigmi C S g il fi g mma d e r may be y large 5 nalscaler 22 is unable to accumulate sample counts.

" 'v ltronics,}icausing erroneous counts. Effectively; the de I ('20 volts or more) and can exceed the capability of the g i 3"" While there has been shown and described a prephotoimult iplier' tube-12 and the signal processing elec ferred embodiment, it is to be understood that various other adaptations and modifications may be made motor system will be dead to all other legitimate pulses l2 and electronics are able to count normalpulsesh within the spirit and scope of the invention.

"fo'i' a finite; period of time. in order to compensate for 1 claim;

' i h Sfl qq intermediate the time bfise 30 andthe 1. In radiation source measuring apparatus having a i gate? an gate fmdmterposed b signal channel transmitting signal pulses from a radiah islgnal gate 20 and the slgnal scaler 22 3 tion source detector to an output device under control AND Both AND gates 50 f of a timer channel providing timing pulses indicative of two'mput a -W the w P Fhereof bellg a predetermined time period for measurement of the coupled together at a af the signal pulses, the combination comprising: output s' h mumvlbramr .Thls output means coupled to the output of said detector for prohlgh thereby normally T' f gates .viding a signal only in response to a detector output .48 and 50. The input to the multivibrator 54 is proin excess ofa predetermined level, and

vldedfrqn an Pf amplifier 56 h? curtime delay means responsive to said signal for simulmm hmmng {exam 5 the.mput of mumv-brator taneously inhibiting the timing pulses in said timing The amplifier 56 biased m a comparator mode channel and the signal pulses in said signal channel b-etwegn'a posmve source of Yoltage i and a nega' for the predetermined time duration of said time I tiv z ource of voltage V with the input thereof on delay means Y coupled to outputiof'the photomum- 25 2 The combination according to claim 1 wherein the i I p l i i tip efation the bias of comparator 56 is established i i i g f f f f f a slfgnal Y v sca er int esi na anne receivin 51 na uses rom 380 that the volt-age of pulse-S from photqmu'ltlpher tube a si nal ate th rou hnormall enabl ed ate fneans said g 12 in'excess of a predetermi'ned voltage,'such as 5 volts, g g b g bl d g I initiate an output through current limiting resistor 58 i means emg Isa e m response to to the'one-shot multivibrator 54 which has a time condc ay means 2 h 'stant of a predetermined value (such as approximately 33 3 combmatlon acFordmg to f i l 1 the t Y 2.0 microseconds) consistent with the anticipated t me 3 measurmg P9? "P e5 3 duration of cosmic interference anticipated. Upon t he m the chamlel F Y t'mmg PulSeS f application f the input m multivibrator 54 the 35 a timer gate which receives timing pulses from a timer output goes low, thereby disabling AND gates '48 base f l through normally gate and 50 'to inhibit pulses from timer base 30 to thetimer ans, said second ga means bemg disabled in gate 32, as well as inhibitsignal pulses through signal SPOnSe said f fi y gate 20 to the signal scaler 22 for the predetermined T combmationaccordmg to Claim 3 where! ti i d, I 40 said time delay means is a one-shot multivibrator hav- Accordingly, it can be seen that by utilization ofthe ing the output thereof coupled to said first and second overload detector herein described, an abnorm'aloverg ns. g

load such as cosi'n'ic energy interference can be sensed, The combination according to claim 4 wherein and the signal pulse counts can be inhibited fromentersaid means coupled to the detector output is a comparing the signal scaler 22 until the photomultiplier tubesaid multivibrator input.

ator providing a signal to I =l= k #l 

1. In radiation source measuring apparatus having a signal channel transmitting signal pulses from a radiation source detector to an output device under control of a timer channel providing timing pulses indicative of a predetermined time period for measurement of the signal pulses, the combination comprising: means coupled to the output of said detector for providing a signal only in response to a detector output in excess of a predetermined level; and time delay means responsive to said signal for simultaneously inhibiting the timing pulses in said timing channel and the signal pulses in said signal channel for the predetermined time duration of said time delay means.
 2. The combination according to claim 1 wherein the radiation source measuring apparatus includes a signal scaler in the signal channel receiving signal pulses from a signal gate through normally enabled gate means, said gate means being disabled in response to said time delay means.
 3. The combination according to claim 2 wherein the radiation source measuring apparatus includes a timer scaler in the timer channel receiving timing pulses from a timer gate which receives timing pulses from a timer base means through normally enabled second gate means, said second gate means being disabled in response to said time delay means.
 4. The combination according To claim 3 wherein said time delay means is a one-shot multivibrator having the output thereof coupled to said first and second gate means.
 5. The combination according to claim 4 wherein said means coupled to the detector output is a comparator providing a signal to said multivibrator input. 